# HYDROCARBONS

Organic compound are composed of only carbons and hydrogen are called hydrocarbons.

ON THE BASIS OF STRUCTURE HYDROCARBONS ARE OF TWO TYPES

1. Acyclic or open chain hydrocarbons

2. Cyclic or closed chain hydrocarbons

Acyclic or open chain hydrocarbons

These hydrocarbons contains open chains of carbon atoms in their molecules. These hydrocarbons are also called aliphatic hydrocarbons.

These aliphatic hydrocarbons are further divided into three groups :

(i) Alkanes

(ii) Alkenes

(iii) Alkynes

Alkanes are saturated compounds and have general formula of ​$$C_{n}H_{2n+2}$$​ where n is any positive number. Example:

$$\begin{matrix}CH_{4}\\methane\end{matrix}$$​ ; ​$$\begin{matrix}CH_{3}-CH_{3}\\(C_{2}H_{6})\\methane\end{matrix}$$​ etc

Alkenes and alkynes are unsaturated compounds and have general formulas of ​$$C_{n}H_{2n}$$​ and ​$$C_{n}H_{2n-2}$$​ respectively. Alkanes are also called paraffins (Latin: parum=little ; affinis=affinity) as they are inert or less reactive to chemical reactions.

Examples of alkenes :

$$\begin{matrix}CH_{2}=CH_{2}\\(C_{2}H_{4})\\ethene\end{matrix}$$​ ; ​$$\begin{matrix}CH_{3}-CH=CH_{2}\\(C_{3}H_{6})\\propene\end{matrix}$$​ etc

Examples of alkynes :

$$\begin{matrix}CH\equiv{CH}\\(C_{2}H_{2})\\Ethyne\end{matrix}$$​ ; ​$$\begin{matrix}CH_{3}-C\equiv{CH}\\(C_{3}H_{4})\\propyne\end{matrix}$$​ etc

Cyclic or closed chain hydrocarbons

These hydrocarbons contains open chains of carbon atoms in their molecules. These hydrocarbons are also called aliphatic hydrocarbons.